Is Merino the world’s best wool?

To understand why Merino wool is so highly valued, it helps to first get a clear picture of wool itself, including its different species, breeds, fiber diameters, and end uses.

Wool is a natural fiber produced by various mammals, including sheep, goats, llamas, alpacas, rabbits, and camels. Among these, sheep wool is the most commercially significant, especially that of the Merino breed, renowned for its fine quality and versatility.

Wool can be categorized based on several factors:

• Species: Wool is primarily obtained from sheep (Ovis aries aries), but also from goats (e.g., mohair), alpacas, llamas, rabbits (e.g., angora), and camels.

• Breed: Within sheep, there are over 1,000 distinct breeds worldwide, each producing wool with unique characteristics. For example, Merino sheep are known for their fine wool, while Romney sheep produce longer, coarser fibers.

• Fiber Diameter (Micron Count): Wool fibers are categorized by diameter as follows, Ultrafine: <15 µm; Superfine: 15–18 µm; Fine: 18–22 µm; Medium: 22–30 µm; Coarse: >30 µm.

• End Use: Wool is processed for various applications, including apparel, carpets, insulation, and upholstery. The intended use influences the desired characteristics of the wool, such as softness, durability, and crimp.

Merino fibers are exceptionally fine, typically 15–25 microns in diameter (thinner than human hair), exhibit higher crimp frequency, and have a softer handle than most standard sheep-wool breeds. This combination of fine diameter, high crimp, and low bending stiffness reduces the mechanical irritation on skin, making Merino wool feel soft and gentle, giving garments a luxurious comfort that makes them extremely versatile.

The exceptional fineness and frequent crimp of Merino fibers allow fabrics to trap large volumes of insulating air, creating warmth without bulk and making garments feel light and comfortable against the skin – an advantage especially noticeable in base layers and next-to-skin apparel.

Merino wool’s fine, crimped fibres and hygroscopic cortex give it exceptional moisture-buffering capacity and what textile scientists call dynamic breathability. Merino fibers can absorb 13–18% of their dry weight in water vapor under standard conditions, compared with about 7–11% for cotton and less than 1% for polyester. Because this absorption occurs inside the fiber structure rather than just on the surface, Merino can hold substantial vapor without feeling wet, creating a stable microclimate next to the skin. This buffering action reduces the risk of sudden cooling after exertion—commonly known as “after-chill” – and helps explain why Merino base layers feel consistently comfortable in stop-and-go activities. Controlled research programs led by NC State University in collaboration with Woolmark and published in the Textile Research Journal confirmed these effects, showing that 100% Merino garments maintain thermal and moisture equilibrium more effectively than cotton, viscose, or polyester, both in lab simulations and in human trials.

Merino wool’s fine, tightly crimped fibres provide superior elasticity and resilience compared to most other wools, allowing garments to stretch comfortably while retaining their shape over time. This performance is rooted in wool’s unique helical keratin protein structure combined with natural crimp, which give the fibre exceptional elastic recovery. Individual wool fibres can be flexed and bent tens of thousands of times before breaking, far surpassing many other natural and synthetic fibers. This resilience not only ensures comfort in wear but also translates into wrinkle resistance, shape retention, and extended garment life when properly cared for. Fundamental studies in textile polymer science confirm that wool’s mechanical behavior is distinct among fibres, with Merino’s finer, higher-crimp fibres amplifying these properties to deliver clothing that is both durable and comfortable.

According to scientific papers, Merino wool can be mechanically recycled up to six times in a closed-loop system without significant loss of fiber length or quality. This high recyclability makes Merino an excellent choice for circular and sustainable fashion.

Merino wool offers inherent flame resistance thanks to its high nitrogen content and bound water, which cause the fiber to char, self-extinguish, and produce less toxic smoke than many synthetics. With a high ignition temperature and a high limiting oxygen index, wool is inherently safer in domestic settings and is widely used in interiors and certain protective clothing applications. At the same time, it provides natural odor resistance: the chemistry of wool and its ability to absorb, trap, and gradually release organic molecules mean that wool garments often retain less body odor after wear than polyester or cotton, allowing them to be worn longer between washes. Controlled sensory testing has shown that wool retains up to 66% less odor intensity than polyester and about 28% less than cotton in worn garments.

After decades in the fashion world, in 2018, we have created the Manteco Academy project, through which we  give webinars, in-person lessons and workshops on eco-design, circular economy and sustainability to numerous fashion schools, technical universities and brands worldwide. Thanks to this educative commitment and our heritage, we are often invited as guest speaker at events, panels, podcasts and conferences about sustainable fashion and circular economy.